The ethanol manufacturing process starts by the cleaning and then the dry-milling of maize grains. The ground grains are mixed with water and enzymes (amylases) to produce a mash where starch hydrolysis occurs. This mash is cooked to kill bacteria that produce undesirable lactic acid. Enzymes are added to the mash to transform starch into dextrose (a saccharification step). After saccharification, yeast is added to start the fermentation process, which produces a beer-like material and carbon dioxide (CO2). The beer passes through a continuous distillation column to yield alcohol at the top of the column. The product that remains at the bottom is whole stillage, which in current practice is separated to produce distillers corn oil (DCO) and distillers' grains. Both byproducts are used as energy and protein sources for ruminants and the distillers corn oil can be used a feed stock for biodiesel production. This invention allows the separation of whole stillage into additional streams contain valuable bio-materials mainly fibers, oil and protein. Greater volumes of oil are recovered for use as a biofuel, animal energy source or for cooking. The ability to separate more DCO creates significant carbon reduction when it is converted to biodiesel rather than being used as an animal feed.
The protein recovered from this invention is in a more concentrated form which increases its value as a protein source for both monogastric and ruminant animals. In addition the main protein in corn is Zein which has been used in the manufacture of a wide variety of commercial products, including coatings for paper cups, soda bottle cap linings, clothing fabric, buttons, adhesives, coatings and binders, recently this protein has been used as a coating for candy, nuts, fruit, pills, and other encapsulated foods and drugs. Additionally Zein can be further processed into resins and other bioplastic polymers.
The fibers recovered from the process of the present invention comprise mostly corn kernel fibers which can be used as raw materials for the production of lignocellulosic ethanol or butanol as well as other chemicals that use glucose and xylose as building blocks.
The present invention results in a significant reduction in energy needed for the grain ethanol co-product separation process and in reduction in the carbon intensity associated with production of grain based ethanol.